1. Field of the Invention
The present invention relates to a soft mold used for soft-lithography in fabricating a liquid crystal display (LCD) and a method for forming a pattern using the same.
2. Discussion of the Related Art
Recently, the importance of a display device as a visual information transmission medium is increasing, and various types of competitive display devices are being developed. In order to hold an important position, the display devices should meet the requirements of low power consumption, being thin and light and having high picture quality.
An LCD, a major product among the flat panel displays (FPDs), has mass-productivity as well as having performance to satisfy those requirements of the display, so it can be commonly employed in various application fields such as a large TV or a computer monitor, etc. and is taking hold as a core display device that may eventually replace the existing cathode ray tubes (CRTs) in the markets.
In general, the LCD is a display device in which data signals according to image information are individually supplied to liquid crystal cells arranged in a matrix form to control light transmittance of the liquid crystal cells to thus display desired images.
The construction of the related art LCD will now be described in detail with reference to FIG. 1.
As shown in FIG. 1, the general LCD includes a color filter substrate, an upper plate, a TFT (thin film transistor) array substrate, a lower plate, and a liquid crystal layer 109.
The color filter substrate includes a substrate 113, a color filter 117 formed on the substrate 113, a black matrix BM 115 formed between color filters 117, and a common electrode 111 formed on the color filters 117 and the BMs 115.
The TFT array substrate 101 includes a substrate 101, a pixel electrode formed at a pixel region (P) on the substrate 101, TFTs, switching elements, and array lines 103 and 105.
On the TFT array substrate 101, the gate lines 103 and data lines 105 are formed to cross each other to define the pixel regions (P), and the TFTs are formed at each crossing of the gate lines 103 and data lines 105. A pixel electrode 107 formed of a transparent conductive layer is formed on the pixel region P.
The liquid crystal layer 109 is formed between the color filter substrate and the TFT array substrate, and made of a liquid crystal material having photorefractive anisotropic qualities.
Although not shown, there may be other elements formed on the LCD, including polarizers attached on both surfaces of the liquid crystal panel, a backlight unit including a lamp and an optical sheets formed at a lower portion of the polarizer of the lower plate, and top and bottom cases that support the liquid crystal panel.
In fabricating most of the flat panel display devices including the LCD, a thin film material stacked on the substrates are patterned through a photolithography process. Patterning through the photolithography process will now be described.
First, photoresist, a photosensitive material, is coated on a thin film desired to be patterned, a photomask with a pattern is aligned thereon, and an exposing process is performed. In this case, the photomask includes transmission regions and a blocking regions. Light which has passed through the transmission region chemically changes the photoresist. The chemical change in the photoresist varies depending on a kind of photoresist. That is, a portion of a positive photoresist which has received light changes to have properties of being dissolved by a developer, and a portion of negative photoresist which has received light changes to properties of not being dissolved by the developed. Hereinafter, the positive photoresist will be described as an example.
The exposed portion of the photoresist in the exposing process is removed by using a developer to form a photoresist pattern on the thin film. Thereafter, the thin film is etched by using the photoresist pattern as a mask, and then, a remaining photoresist pattern is removed, to form a thin film with a certain pattern.
The photolithography process may be used three times to five times in the processes of forming a gate electrode, forming an active layer pattern, forming source and drain electrodes, forming a contact hole and forming the pixel electrode.
However, as mentioned above, the photolithography process requires the high-priced photomask and the complicate steps such as exposing and developing, resulting in excessive processing costs and difficulty in managing production yield.